This invention generally relates to stapling devices and, more particularly, to a hand held stapler with built in storage space for additional staples.
Hand held staplers in the prior art have generally attempted to combine the functions of desk staplers, wall tacking devices and hand held staplers in a compact and portable unit. While a desk stapler is intended to rest on a flat surface and operate in response to downward pressure from a user's hand, the hand held unit is intended to operate when squeezed by a hand, and must therefore be compact and lightweight. Additionally, a stapler may act as a tacking unit when the base portion containing the anvil is swung away from the head portion, thereby allowing stapling of items to large continuous surfaces such as walls. However, desk staplers are generally intended to fasten together large volumes of material, and must have a flat base member in order to provide stability on a desk top surface, while a hand held unit is preferably designed to fit comfortably within the curved surfaces of the human hand. Therefore, attempts in the prior art to combine hand stapler and desk stapler functions have met with only limited success.
The stapling of bindings for publications such as magazines and flyers has been the subject of many stapler designs in the prior art. The problem has been to place a staple in the binding and parallel to the length thereof so as not to impede the folding and closing of the publication. One approach to this problem is illustrated in U.S. Pat. No. 3,451,606 to Jacobson in which the stapler head pivots at the staple delivery point over the anvil while remaining connected to the anvil by means of a V-shaped base plate. The binding of the publication is inserted lengthwise within the V of the base plate, so that the anvil and stapler head are aligned correctly with respect to the binding. The staple is then inserted in a normal fashion. However, the stapler is no longer stable on the desk surface because its center of gravity is no longer directly above the base plate surface which rests on the desk top.
Some prior art staplers have also provided extended staple magazines or separate staple storage containers, but these have proved bulky and unfit for hand held stapler design. An example is shown in U.S. Pat. No. 3,302,842 to MacEachron. The stapler head therein is permanently pivoted atop one end of a U-shaped base plate, so that the staple delivery point is over an anvil mounted at the other end of the base plate. Since only the anvil portion of the base plate is intended to be placed beneath the binding of a publication, the other portion of the base plate is always exposed and carries a conventional container for additional staple loads. The geometry and bulk of this unit is clearly inappropriate for a hand held stapler.
A spring is commonly used within the staple magazine of staplers to urge the staple load toward the staple delivery point. The force applied to the load by the spring varies in direct proportion to the length of the spring, so as staples are delivered and the spring compresses the load, the spring length changes and the force applied increases or decreases accordingly. Where a spring is 50% to 100% longer at the beginning of a load than at the end of the load, as is common in the prior art, the force applied to the load will correspondingly be 50% to 100% greater at the beginning than at the end. This large variance in the spring force applied to the load contributes to the tendency of the last few staples in a load to jam upon delivery.